Di-p-toluenesulfonic acid salt of N-ethyl-N-methoxyethyl-3-methyl 1,4 benzenediamine

ABSTRACT

The p-toluenesulfonic acid salts of certain p-phenylenediamine color developing agents have been found to possess extraordinarily and unexpectedly high solubility in aqueous alkaline solution. Thus, extremely concentrated solutions of these materials can be prepared to provide developer &#39;&#39;&#39;&#39;concentrates&#39;&#39;&#39;&#39; which are extremely economical to ship and working developer solutions which possess abnormally high developing agent concentrations and which are therefore capable of producing unusually high dye density levels in very short periods of time. Specifically preferred among these pphenylenediamine salts are the di-p-toluenesulfonic acid salts of 3-alkyl and 3-alkoxy N-alkyl-N-alkoxyalkyl-p-phenylenediamine developing agents.

Schellenberg et al.

DI-P-TOLUENESULFONIC ACID SALT OF N-ETHYL-N-METHQXYETHYL-3-METHYL 1,4 BENZENEDIAMINE Inventors: Dietmar Schellenberg; Richard L.

Bent, both of Rochester, NY.

Assignee: Eastman Kodak Company,

Rochester, N.Y.

The portion of the term of this patent subsequent to Apr. 25, 1989, has been disclaimed.

Filed: Jan. 23, 1974 Appl. No.: 435,813

Related U.S. Application Data Division of Ser. No. 204,725, Dec. 3, 1971, Pat. No. 3,816,134.

Notice:

U.S. Cl 260/501,l9; 260/505 N; 260/563 Int. Cl. C07C 93/14 Field of Search 260/501.2, 501.19

References Cited UNITED STATES PATENTS 4/1972 Bent et al. 96/22 1*Sept. 23, 1975 3,658,525 4/1972 Bent et al. 96/22 Primary Examiner-Bemard Helfin Assistant Examiner-G. Breitenstein Attorney, Agent, or FirmA. P. Lorenzo [5 7] ABSTRACT The p-toluenesulfonic acid salts of certain pphenylenediamine color developing agents have been found to possess extraordinarily and unexpectedly high solubility in aqueous alkaline solution. Thus, extremely concentrated solutions of these materials can be prepared to provide developer concentrates which are extremely economical to ship and working developer solutions which possess abnormally high developing agent concentrations and which are therefore capable of producing unusually high dye density levels in very short periods of time. Specifically preferred among these p-phenylenediamine salts are the di-p-toluenesulfonic acid salts of 3-alkyl and' 3-alkoxy N- alkyl-N-alkoxyalkyl-p-phenylenediamine developing agents.

1 Claim, N0 Drawings DI-P-TOLUENESULFONIC ACID SALT OF N-ETHYL-N-METI-IOXYETHYL-3-METHYL 1,4 BENZENEDIAMINE This application is a division of U.S. Pat. application Ser. No. 204,725 filed Dec. 3, 1971. and issued June ll, 1974 as U.S. Pat. No. 3,816,134.

This invention relates to color photography and more particularly to color photographic developing agents which are capable of forming unusually highly concentrated aqueous alkaline solutions and, hence, provide faster rates and shorter times of color development.

In the process of color photography, it is known to use p-phenylenediamine developing agents in conjunction with couplers to produce colored images. A summary of this process is described by Thirtle et al, Encyclopedia of Chemical Technology, Vol. 5, pp. 812-845 (1964), John Wiley and Sons, Inc. The color developing agent is oxidized by the silver halide in the presence of a latent image in a photographic element to produce silver metal and oxidized color developing agent, The oxidized color developing agent then couples with color-producing compounds present to produce a dye image-wise with respect to silver development.

Color development of the differently sensitized emulsion layers in color photographic elements containing nondiffusible couplers is advantageously performed in a single color development step to produce a color negative image reproduction when this development step is the first development step, or to produce a color reversal image if a negative black-and-white development step is used followed by a step in which the residual unexposed and undeveloped silver halide is made devel- I opable and then color developed. In reversal color photographic elements that do not contain nondiffusible couplers, diffusible couplers are used in the aqueous alkaline color developer solutions that are used to selectively color develop one silver halide emulsion layer at a time. The reversal processing of such a multicolor, multilayer element (containing no incorporated couplers) requires a negative black-and-white process followed by a step in which residual unexposed and undeveloped silver halide in each emulsion layer is selectively made developable, then that layer is color developed with a color developing solution containing a diffusible coupler that forms a nondiffusible dye that is complementary in color to the light-sensitivity of that layer, then the unexposed and undeveloped silver halide in a second emulsion layer is selectively made developable and color developed with another color developing solution containing a diffusible coupler that forms a nondiffusible dye that is complementary in color to the light-sensitivity of that layer. Following completion of the color development, the. silver and any residual silver halide are removed by silver bleaching and then fixing the photographic element. In any such color process, it is important that as large as practical and possible a quantity of color developing agent be brought into contact with the exposed, black-andwhite developed etc. element within the shortest possible period of time so that maximum density dye images are produced with optimum efficient usage of the silver present in the photographic element in the minimum amount of time.

Also, in recent years, in order to eliminate the need for complex, expensive mixing equipment at the processors location, it has become the custom in the trade to provide processing chemicals in the form of concentrated aqueous solutions which, while they are easier to dissolve or dilute with water than the dry processing chemicals, provide similar results. This dissolution of dry chemicals often required several hours of intense mixing with expensive equipment, and sometimes resulted in solutions containing substantial amounts of undissolved solute which rendered practical usage thereof impossible.

In view of the costs of shipping such concentrates attempts have continuously been made to reduce the amount of water which had to be shipped in the concentrates and consequently to increase the concentration of the working chemicals (i.e. developer, bleach, fix, etc.) to the highest practical levels which provide a stable solution. I

Thus, in the photographic arts there has existed a definite need and desire for, among other things, more concentrated solutions of p-phenylenediamine color developing agents which provide faster rates of color development and hence shortened color development times for color photographic elements and simultaneously permit the preparation of extremely concentrated solutions of color developer for shipment from the supplier to the processor customer.

Among the prior art suggesting methods for increasing the solubility of p-phenylenediamine developing agents are a large number of references which suggest the formation of the inorganic, e.g. I-ICl, salts of such compounds. More recently, attempts to increase the solubility of these materials have been directed to the formation of organic salts thereof. Among this art is U.S. Pat. No. 2,618,558 to Vittum et al. which suggests the use of a benzene sulfonate, of the formula:

wherein R is hydrogen or a lower alkyl radical and M is ammonium or alkali metal, to increase solubility. British Pat. No. 837,49l to Imperial Chemical Industries Ltd. suggests the use of an acid with the formula X-ArSO H wherein Ar represents an arylene radical and X is a carboxylic or sulphonic acid group.

As will be demonstrated hereinafter, the method and compositions of the present invention provide solubilities on the order of 10 to 30 times greater than those demonstrated by these prior art methods.

SUMMARY OF THE INVENTION It has now been discovered that the p-toluenesulfonic acid salts of p-phenylenediamine color developing agents are unusually soluble in aqueous alkaline solutions of the type used as working solutions in the color development of multilayer color photographic elements and as concentrates for the shipping of such color developers from the chemical manufacturer to the processor.

DETAILED DESCRIPTION OF TI-IE INVENTION According to the present invention the p-toluenesulfonic acid salts of color developing agents havingthe formulas:

a NH wherein R, and R are alkyl groups having from 1 to 4 carbon atoms, i.e. methyl, ethyl, propyl, butyl, etc., hydroxy alkyl groups having from 1 to 4 carbon atoms, i.e. hydroxy methyl, hydroxy ethyl, etc., or alkoxy alkyl groups having from 2 to 8 carbon atoms, i.e. methoxy methyl, methoxy ethyl, ethoxy methyl, ethoxy ethyl, etc. and R is an alkyl or alkoxy group having from 1 to 4 carbon atoms, have been found to have unusually and unexpectedly high solubility in aqueous alkaline solution.

The p-toluene sulfonic acid salts of these developing agents are generally represented by the following generic formula:

n NH,

wherein m is an integer of 2 to 4; R is an alkyl group having 1 to 4 carbon atoms, e.g. methyl, ethyl, propyl, butyl, etc. and R is an alkyl group havingfrom 1 to 4 carbon atoms, e.g. methyl, ethyl, propyl, butyl etc., or an alkoxy group having from 1 to 4 carbon atoms, e.g. methoxy, ethoxy, propoxy, butoxy. These compounds have been found to be extremely and unexpectedly more soluble in aqueous alkaline solutions than even the toluenesulfonic acid salts of other pphenylenediamine developers which also demonstrate improved solubility. Thus, the formulation of even more concentrated concentrates of these materials in aqueous alkaline solution is possible. This provides working color developer solutions which yield higher development rates due to the higher developing agent levels. Furthermore, color developing agents falling within the aforementioned generic Formula I possess other substantial processing advantages which will be discussed in greater detail hereinafter and which are described in substantial detail in U.S. Pat. application Ser. No. 94,992 filed Dec. 3, 1970 and issued Apr. 25, 1972 as U.S. Pat. No. 3,658,525 and application Ser.

No. 94,993 filed Dec. 3, 1970 and issued Apr. 18, 1972 as U.S. Pat. No. 3,656,950. These applications are incorporated herein by reference. Furthermore, the high solubility of these salts permits the use of higher developer concentrations in PODS of the type used in the picture in-aminute photographic system of the type described in U.S. Pat. Nos. 3,537,851 and 3,537,852 to Bloom issued July 1, 1968. The advantages of having high volume of color developer present in an extremely small amount of solvent in these and other photographic systems will of course be readily apparent to those skilled in this art.

Typical representative examples of the preferred color developing agents of Formula 1 are the following:

1. N-Ethyl-N-methoxyethyl3-methyl-pphenylenediamine 2. N-Ethyl-N-methoxybutyl-3-methyl-pphenylenediamine 3. N-Ethyl-N-ethoxyethyl-3-methyl-p phenylenediamine N-Ethyl-N-methoxyethyl-3-n-propyl-pphenylenediamine 5. N-Ethyl-N-methoxyethyl-3-methoxy-pphenylenediamine 6 N-Ethyl-N-butoxyethyl-3-methyl-pphenylenediamine In general, the color developing agents of Formula 1 are prepared by reacting the appropriate m-alkoxyalkyl chloride or bromide with the appropriate N-ethyl- 3-alkyl-aniline or N-ethyl-3-alkoxyaniline. The tertiary anilines formed by this reaction are then either nitrosated or azo-coupled followed by catalytic hydrogenation to give the corresponding p-phenylenediamine. The p-toluenesulfonic acid salts of these materials are generally prepared by forming the 4-(2,5- Dichlorophenylazo) derivative of the pphenylenediamine derivative of Formula I, reducing the azo dye and adding p-toluenesulfonic acid.

Specifically, the di-p-toluenesulfonic acid salt of Preferred Color Developing Agent 3 is advantageously prepared by the following sequence of reactions:

(1) N-(B-Ethoxyethyl )-N-ethyl-3-methylaniline A mixture of 135 g (1 mole) of N-ethyl-3-methylaniline, 153 g (1 mole) of 2-bromoethyl ethyl ether (purified by treatment with sodium bicarbonate and distillation), 88.2 g. (1.05 mole) of sodium bicarbonate, 1100 ml of ethanol and 290 m1 of water are refluxed for a total of 64 hours. The ethanol is removed by distillation and the oil layer is extracted with ether; the ether extracts are dried and concentrated, followed by distillation of the residual oil under reduced pressure. After removal of the lower boiling foreruns, the fraction, b.p. 9295C/lmm (overheats readily) is collected. The yield ofl is approximately 4-( 2,5-Dichlorophenylazo)-N-( B-ethoxy-ethyl )-N- ethyl-3-methylaniline:

A total of 44 g (0.27 mole) of 2, S-dichloroaniline is dissolved in a mixture of 240 ml concentrated hydrochloric acid and 700 ml of water by heating with stirring on a steam bath. When solution is complete, the reaction mixture is cooled with stirring to 5C, the hydrochloride salt precipitating out. A solution of 19 g (0.275 mole) of sodium nitrite in ml of water is added dropwise with stirring, keeping the temperature at about 5C. When complete,'stirring is continued for another 20 minutes and the excess nitrous acid destroyed by the addition of sulfamic acid. The cold diazonium solution is filtered and at once added to a cold solution of 56 g (0.27 mole) of I in dilute hydrochloric acid. Considerably more water is added and with stirring a total of 250 g of sodium acetate is added to promote the coupling. After standing for a few hours, the azo dye is filtered off and at once recrystallized from approximately 1000 ml of ethanol. This is followed by a second recrystallization from 900 m1 of ethanol, filtering hot and cooling to about 25C. The yield of II,

m.p. 74.5 755C, is 77%. 4-Amino-N-( B-ethoxyethyl )-N -ethyl-3-methylaniline,

di-p-toluenesulfonic acid salt (Developing Agent 3) Three grams of the azo dye, II, is reduced on a Parr shaker using 300 ml of absolute alcohol and Raney nickel as catalyst. When complete, the catalyst is filtered off and washed on funnel with more ethanol. A solution of 3 g (0.0158 mole) of p-toluenesulfonic acid (hydrate) in 50 ml ethanol is added and the solution is then concentrated to dryness (partial vacuum). The semisolid is then slurried thoroughly with 35 ml of hot isopropyl alcohol, gradually becoming nicely crystalline. The mixture is cooled to about 25C and allowed to stand undisturbed overnight. The developer salt is filtered off and washed in a funnel with small portions of isopropyl alcohol. The yield of Developing Agent 3, m.p. 2l42l6C, is approximately 70%.

The di-p-toluenesulfonic acid slat of Color Developing Agent 5 is advantageously prepared similarly to developing agent (3), using N-ethyl-3-methoxyaniline,

and 2-bromoethyl methyl ether as starting materials.

(Ill) N-Ethyl-3-methoxy-N-(B-methoxyethyD-aniline A mixture of 100 g (0.661 mole) of N-ethyl-3- methoxy-aniline, 92 g (0.661 mole) of 2-bromoethyl methyl ether, 55.8 g (0.6665 mole) of sodium bicarbonate, 1000 ml of ethanol and 280 ml of water is refluxed for a total of 68 hours. The alcohol is removed under partial vacuum and the oil layer extracted with ether; the ether extracts are dried and concentrated. The residual oil is then distilled under reduced pressure. The yield of III, b.p. l49 l5lC/8mm, is 35%.

4-( 2 ,5 -Dichlorophenylazo )-N-ethyl-3-methoxy-N-( B- methoxyethyl )aniline This azo dye is prepared from III in exactly the same way as described for the preparation of the azo dye used for developing agent (3). The yield of IV, m.p. 9496C (from ethanol), is approximately 73%.

The di-p-toluenesulfonic acid salt of 4-amino-N-ethyl-3-methoxy-N-( B-methoxyethyl)ani line (Developing Agent 5) Exactly 4.86 g (0.127 mole) of the azo dye, IV, is re duced on Parr shaker, using 300 ml of absolute alcohol and Raney nickel as catalyst. When complete, the catalyst is filtered off, washed on funnel with more alcohol. A total of 4.84 g (0.0254 mole) of p-toluenesulfonic acid (hydrate) in 50 ml of ethanol is added; no precipitate occurss and the solution is concentrated to dryness under partial vacuum. The gummy residue is then dissolved in a small quantity of absolute alcohol and a large excess of ethyl ether is added; the developer salt again comes out as a gum; the solutionis cooled thoroughly (refrigerator) to precipitate the suspension and then the ether-alcohol layer is decanted. This treatment is repeated twice more to remove all of the regenerated 2,5-dichloroaniline. Finally, the developer salt is slurried thoroughly with ether only, gradually becoming crystalline; it is dried in a vacuum oven. The yield of Developing Agent 5, m.p. l60162C, is 62%.

The di-p-toluenesulfonic acid salt of Color Developing Agent 1 is made in a manner similar to the synthesis described for the corresponding acid salt of Color Developing Agent 5, excepting that an equimolar amount of N-ethyl-3-methylaniline is'us'ed in place of N-etliyl- 3-methoxyaniline. I

The dip-toluenesulfonic acid salt of Color Developing Agent 2 is made in a manner similar to the synthesis described for the corresponding acid salt of Color Developing Agent 5, excepting that an equimolar amount of w-bromobutyl methyl ether is used in place of 2- bromoethyl methyl ether.

The di-p-toluenesulfonic acid salt of Color Developing Agent 4 is advantageously made in a manner similar to that described for the corresponding acid salt of Color Developing Agent 3, excepting that an equimolar amount of N-ethyl-3-propylaniline is used in place of N-ethyl-3-methylaniline.

Still other color developing agents of Formula I are made using the synthesis illustrated herein using the appropriate starting materials and intermediates.

The following examples are included for a further understanding of our invention and the utility thereof:

EXAMPLE 1 Saturated solutions of various of the color developing agents described herein were obtained by gradually adding small amounts of developer salts to water under nitrogen atmosphere and adjusting the pH with alkali to pH 10.0 after each addition. Saturation was indicated by the initial appearance of turbidity (further ad dition caused phase separation). The solutions were an alyzed for developing agent and the results converted to g/l or mol/l of substance in the saturated solution. The results are tabulated in Table 1.

EXAMPLE 2 The procedure described in Example 1 was repeated with solutions of different pH values. The results are tabulated in Table 2.

EXAMPLE 3 The procedure described in Example 1 was repeated by adding the developer salt to sodium carbonate solutions of 25, or 320 g/ l respectively, to simulate actual color developer solutions. The results are tabulated in Table 3.

EXAMPLE 4 The procedure described in Example 1 was repeated by adding the developer salt to solutions with 50, 100 or 150 g/ l NaPTS. The results are summarized in Table 4.

EXAMPLE 5 The procedure described in Example 1 was repeated by adding the developer salt to a solution with g/ 1 NaPTS. The results are given in Table 5.

7 8 Table l Tab1 Na PTS Solubility of iz gg l g added to the solution Developer F (PTS Salt)* Developer Salt R, R2 g/l M 5 690 g" l 3M B HCl c n CH3 19 .l

C HZSO4 CZHQOH H 9() 32 ROOm temperature; pH 10.0

D H 50 e l-LOH CH 90 .3

D 2 PTS* C H OH CH 650 1.2 T

E 2 PTS* CHZCHOHCHZOH CH 490 .9 1 The data m ables 1 5 Sho F 2PTS* C l-L0CH CH; 690 3 Table l: The evaluated p-phenylenedlamlnes wlth F CJLOCHJ CH3 84 inorganic (and some organic counteracids have a solubility in water (room temperature, pH of about 0.1 to 0.3 mol/ 1 whereas the PTS salts show solubilities of approximately 1.0 mol/l. Differences in the structure of the color developer are of minor importance.

PTS: p-toluene sulfonic acid NSA: l 4-naphthaler|e disulfonic acid Table 2: Small changes in pH (pH 10 i l or 2 units) T have little influence on the above results.

Table 3: Higher concentrations of inorganic salts in the solution decrease the solubility of pphenylenediamines substantially, both for the inorganic z and the PTS acid salts of the developing agents. Table 4: The solubility of p-phenylenediarnines with inorganic counteracids can be increased by adding Na- Table 2 PTS to the solution. in the given example this increase is approximately 8 fold when 150 g/ l NaPTS have been Solubilitics at Other added to the SolutionpH Values Table 5: Addition of NaPTS to solutions which al- PH 5/] M ready contain the PTS salt of a p-phenylenediamine is C H2504 L7 95 34 not desirable. The solubility decreases. The PTS intro- 3 PTS 8 13 duced with the developing agent obviously is sufficient F PTS to give the effect of increased solubility.

The following Example 6 will serve to further distinguish the method and compositions of the present in- Table 3 vention from those of the prior art.

Solubility in N co. Solution EXAMPLE 6 Devemper sun 25 (g hl g simulate an actual working developer solution solublllty measurements were obtained by adding the de- C 1 (-52 33 veloper or salt in weighed portions to a known volume F 2 PTS -7'00gfl -'700 g .j g/l of pH 10 phosphate buffer (p. 0.75) to which had (1.3M) (1.3M) (.3M) been added 2 g/l of Na SO The mixture was stirred until solution was obtained (absence of scattered light) and the pH adjusted back to 10.0 by addition of NaOH Table 4 (pellets). This process was repeated until a portion of the compound no longer dissolved. A repeat of the test Na PTS Solubility using smaller portion additions near the solubility limit added to the solution Developer B (H ul establishes the solubility of the compound under these 0 9 ll 0 I M conditions. Storage of the solutions for several days at g" 2 I 50 room temperature insures against supersaturation. The I00 g/l 0 g/ .2 data shown in Table 6 represent the average of 3-4 rep- [50 g/l -l45 g/l 0.67M Gates TABLE 6 Solubilitv in MI] (of solvent) g/l (of solvent) Aromatic Primary Amine Free Base HCl Salt C,;H SO ,H Salt PTS Salt Z.5(CH;,) C,;H; SO;,H Sal! The foregoing Table 6- clearly demonstrates thatin each case the PTS salt of the-primary aromatic-amine was more soluble than one or more of either the free base, the inorganicacid salt, the benzene sulfona-te salt of U.S. Pat. No. 2,618,558 or the closelyanalogous 2,5-

(Cl-l C H SO H.

Thus, it should be clear that use of the PTS salts of p-p'henylenediamine developing, agents, preferably those 'ofthe type defined by Formula lL-and even more advantageously thoseof Formula Ill, aboyepermits dissolution of substantially Iargerquantities of developing agent in a given amount ofsolvent than has heretofore been possible. i Q

The utility of the PTS salts described hereinabove and of the aqueous alkaline solutions prepared therefrom in photographic processing systems will be readily recognized by those skilled in the photographic arts, however, concrete examples of this utility as well as the advantages which can be achieved when specific members of the'class of p-phenylenediamines are used as-developing agents are presented in the aforementioned U.S. Pat. Nos. 3,656,950 and 3,658,525 which have been incorporated herein by reference.

Generally, these organic acid salts of pphenylenediamine developing agents will be used in aqueous alkaline solution at a pH avove about 8 and preferably above about 9.5. The concentration of the salt present in the solution will be dependent upon the concentration of developing agent which is required. Generally, this concentration will range from about 0.5 to about g/l in working developer compositions depending upon the particular system to which the developer is to be applied. However, in concentrates suitable for shipping and dilution prior to use as working developers, the concentration of PTS salt is limited only by its own solubility and the stability of such a solution under a given set of conditions of storage and shipping. Thus, in working solution the concentration of the PTS salt is limited by the use to which the solution is to be put and hence the amount of developer which it is sought to have present therein. Theoretically, at least insofar as the specific color developing agents described in Formula II hereinabove are concerned, the problem of color developer solubility no longer exists since the limits of the solubility of the PTS salts of these materials are generally at or well above the practical concentration limits for those materials in working solutions.

As demonstrated by the foregoing examples the instant invention demonstrates the following distinct advantages:

A. p-phenylenediamines with p-toluenesulfonic acid (PTS) counteracid have a considerably higher solubility than the same compounds as free bases which are highly unstable and dissolve poorly or as salts with other organic or inorganic counteracids which have only slightly improved solubility;

B. the addition of sodium benzene sulfonate at the levels taught in U.S. Pat. No. 2,618,558, i.e. -200 g/l increases the solubility of the model compounds from 0.007 mole/l to 0.035 mole/1 for the highest concentrations of benzene sulfonate (data derived from U.S. Pat. No. 2,618,558). Using the PTS salt of a pphenylenediamine increases the solubility to more than 1 mole/1 implying that together with the developing agent amounts of more than 388 g/l of Na-PTS would have been added in that case.

Thus,..it has now been discovered that compositions having the following generic structure:

wherein n is either 1 or 2, R, and R are lower alkyli hydroxy lower'alkyl, or alkoxy loweralkyl, and R is lower alkyl'or lower alkoxy, have unexpectedly high solubility in aqueous alkaline solutions of the type utilized for the color development of color photographic elements and thathenc'e they possess all of the above-described advantages incident to such unusually high solubility.

Solutions of these materials can of course include all of the addenda incident to developer compositions of the t ype dcscribed including but not limited to color developer stabilizing agents, alkali metal chloride, alkali metal bromide, sulfite ion and the alkali metal salts of weak acids. v

Solutions of the PTS salts of the color developers described by Formulas l and II are formed simply by dissolving the same in an aqueous alkaline solution. Generally the working developer solutions can comprise up to about 200 g/l of color developing agent although much lower concentration levels on the order of from about 0.5 to about 15 g/l will provide satisfactory results in conventional processes as mentioned above. Concentrations above this level are useful when it is sought to speed up the development rate and/or to increase the throughput capability of the developer bath. Thus, in conventional practice, concentrated aqueous alkaline solutions of the PTS salts of the developing agent, i.e. those solutions having concentrations above about 200 g/l will generally be prepared for shipping and storage. These concentrates" may contain as much of the salt as tolerable in the particular system so that precipitation or phase separation does not occur. When received by the consumer-processor these concentrates will be diluted with water to provide working solutions with color developer agent concentration of up to, for example, perhaps 200 g/l. The concentrate will generally contain a sufficient amount of alkali i.e. sodium, potassium or ammonium hydroxide or sodium or potassium carbonate to provide when dissolved in water to yield the desired developing agent concentration, a solution of the developing agent which has a pH above about 8 and preferably above about Since the active developing agents of working developer solutions prepared from such concentrates are pphenylenediamine developing agents they will include small amounts of sulfite ion which stabilize the developing agent against aerial oxidation during storage as a concentrate and while in use as a working developer solution.

Furthermore, in addition to the other addenda such as benzyl alcohol, (0-l5 ml/l) alkali metal chlorides (0-15 g/l alkali metal bromides (0.1-1.0 g/l alkali metal or ammonium sulfite (0.1-5.0 g/l) and alkali metal or ammonium salts of weak acids (10.0-50.0 g/l) which are conventionally present in pphenylenediamine developer solutions of this type in the concentration ranges shown in parentheses, it is generally desirable to incorporate a stabilizer composition which insures that the developer does not separate into phases at levels of from about 0.1 to about 5.0 g/l. Two such stabilizers are hydroxylamine sulfate and dihydroxyacetone.

Once workin'g" developing solutions of the novel PTS Salts of p-phenylenediamine developing agents described hereinabove are prepared, their use is in the conventional fashion well known to those skilled in the art. In brief, the color development of a multilayer silver halide color emulsion layer is accomplished by contacting the silver halide with an aqueous alkaline solution of a p-phenylenediamine developing agent in the presence of a coupler that reacts with oxidized developing agent to form a dye. In accordance with the present invention the improvement in such a process comprises using the p-toluenesulfonic acid salt of the pphenylenediamine developing agent as the developing agent to provide higher concentrations of developing agent than would normally otherwise be possible. It is of course possible to use these salts to obtain conven tional levels of developer concentrations, the advanthe invention and that the same should not be limited' except as specified in the appended claims.

We claim:

1. A compound of the formula (HSO; CH 

1. A COMPOUND OF THE FORMULA 